If you want to take good photographs, you need good light. Luckily for us, you can get reels and reels of LEDs from China for pennies, power supplies are ubiquitous, and anyone can solder up a few LED strips. The missing piece of the puzzle is a good enclosure for all these LEDs, and a light diffuser.
[Eric Strebel] recently needed a softbox for some product shots, and came up with this very cheap, very good lighting solution. It’s made from aluminum so it should handle the rigors of photography, and it’s absolutely loaded with LEDs to get all that light on the subject.
The metal enclosure for this softbox is constructed from sheet aluminum that’s about 22 gauge, and folded on a brake press. This is just about the simplest project you can make with a brake and a sheet of metal, with the tabs of the enclosure held together with epoxy. The mounting for this box is simply magnets super glued to the back meant to attach to a track lighting fixture. The 5000 K LED strips are held onto the box with 3M Super 77 spray adhesive, and with that the only thing left to do is wire up all the LED strips in series.
But without some sort of diffuser, this is really only a metal box with some LEDs thrown into the mix. To get an even cast of light on his subject, [Eric] is using drawing vellum attached to the metal frame with white glue. The results are fairly striking, and this is an exceptionally light and sturdy softbox for photography.
Where does he get those wonderful toys?
He makes them. Look at some of his other videos.
The strips are in parallel, not series. He even says so in the video.
I’ve become fond of using the diffused LED and CCFL backlighting from modified broken/discarded televisions. in the past few years i’ve done 10 or so of these. the power used/wasted, the heat dissipation, the bulk/weight, and the limited angulation during operation, has not posed (m)any problems. removing the LCD panel w/ adhered polarizer takes all of 10 minutes; the resultant light is perhaps 3x brighter than that of the unmodified TV’s showing an all white picture. used TV’s and computer monitors grow on trees around here, varying in price from FREE→$10 each, sized 14″ on up to 36″. YMMV. hth.
https://i.imgur.com/JZwlm8r.jpg
That’s neat, and if the monitor/TV has a VESA mount on the back, you can get a stand, fully articulated and a professional looking light-box for the price of the stand and the time to remove the LCD and polariser.
Don’t many monitors use side-lighting though? I was under the impression that the full screen LED system is only now getting off the ground to do local dimming for HDR purposes, but before that it was mainly side-lighting.
side lighting is just fine too: most tv’s/monitors include a [thin] reflective back sheet, a [thicker] acrylic sheet with dimpled patterns to provide even light distribution, and then 1or2or3or4 thin sheets to further diffuse the light. (even the 1″-5″ LCD’s in toys/displays use these layers and are edge lit.) backlighting LED on strips are often in series requiring 9V, 12V sometimes all the way up to 48V on large TV’s. tip for PCB markings: ‘A’ is anode(+) and ‘K’ is cathode(-).
https://www.quora.com/What-is-an-LED-diffuser-sheet-How-does-it-work-in-LED-lighting
I built two almost identical panel lights using 24V daylight high CRI not-from-China LED strips that cost an arm and a leg (160€ / $200 for 5 meters). I think the strips are 1000 lumens / m which results in 2500lm max light output for each of the lights. The box I bent to shape with help of some aluminium extrusion bits as clamps and a hammer. I pop rivetet the corners. For light diffusion I bought acrylic sheets made for the exact purpose from an acrylic cutting / sign making shop. They said the sheet is specially and specifically designed for diffusing LED light (I’m guessing it means it’s efficient in spreading light evenly from bright and small spot light sources) and it didn’t cost that much even including cutting.
Since I needed variable light output, I wrote a short Arduino code and threw some FETs & push buttons in the mix to control the light level with PWM. I needed to up the base frequency of the Arduino (I cranked it to the max to be on safe side) to get rid of flicker, which was very very obvious especially when shooting video with standard (PWM) fequency of Arduino. To make it “compatible” with the adjustment steps of cameras (aperture steps), I’m halving/doubling the PWM level on each power step. This means the full light output level is 100%, one step down is 50% (that’s one full stop in photography language), then 25% and so on. If you have been tinkering with light levels, you know this makes the light adjustment look kinda uniform even though the steps seem totally uneven when comparing the figures on paper. And as said, it also plays nice with cameras.
As power source I’m using some old 6S LiPo batteries I have my drawers full of as a legacy of RC electric helicopter & multicopter endeavors from the past. To protect the batteries I wrote a simple voltage monitoring into the code which starts blinking the lights every now and then when the battery runs low. This has proven handy and does no harm while taking photos. For video work blinking lights are completely out of the question, though.
Upside of using batteries is portability. I can just grab the lights with me and go to location. The downsides are of course batteries running flat but also inconsistent light level. Since I’m running the lights using hardcoded PWM levels straigt from the battery with no light level feedback or voltage adjustment, the light level goes down when battery voltage drops. For time being I have not done anything to fix the issue. Of course it could be fixed simply by measuring the light output at different voltage levels and adjusting the PWM percentages accordingly. This would mean restricting the highest possible light output level, though.
Next I was planning to order some cheap high CRI LED strips from China and see how good they are. I need to build a bigger and brighter light for portrait photography and building it with the super expensive branded daylight high CRI strips is out of the question. The downside is (according to my experience with ordering LED strips form China) uncertainty on light color. There’s no actual guarantee on color temperature of the LEDs, even more so when ordering them from China. They will most likely be somewhat different to the LED strips I currently have. And even more sadly they will most likely to be off if I order the strips from China in separate batches…
Not to worry with the color temperature any more. OSRAM gas thse Value Flex product portfolio where they have very nice CRI and lm/m products that won’t cost you an arm and a leg. If you really need Quality then look for the LINEARlight Flex portfolio but for most of us the Value Flex will do just fine.
I would worry about the LEDs actually having a linear response to the PWM signal. Have you tested that 50% on is one stop?
And if so, then please share the part number of those LEDs. I need to get a batch.
Nope, I have not tested that. That will come in v2 of the thing together with voltage drop compensation. Adjustments are done visually anyways when shooting, so it’s enough to be even somewhat in the right ball park.
I wonder how much it would cost to buy a used LED or LCD TV and give it a white signal…
That’s not the best solution, but you’re getting close. An LCD panel, whether it’s backlit by LEDs or cold-cathode fluorescents, loses more than half its light in its polarizers. The thing to do is disassemble an LCD panel and REMOVE the LCD and polarizers, leaving only the backlight and diffusion system. In most cases this involves bending some metal tabs straight, then pulling the frame apart. Of course you still have to keep the portion of the electronics that drives the LEDs or CCFL tube.
Thanks I think i might use this for my next attempt at a flatlay